<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./jq-3.6.0.js"></script>
</head>

<body>
    <button class="bn1">1</button>
    <button class="bn2">2</button>
    <button class="bn3">3</button>
</body>
<script>
    $('.bn1').on('click', function() {
        $('.bn2').get(0).click();
    });
    $('.bn2').on('click', function() {
        alert(222222)
    });
    setTimeout(function() {
        //$('.bn2').get(0).click();
        //var bn2 = $('.bn2').get(0);
        // bn2.trigger('click');
        //jq 自动触发
        // $(".bn2").trigger("click");
        // $('.bn2').triggerHandler("click");
    }, 2000)
</script>

</html>